Early Development and Putative Primordial Germ Cells Characterization in Dogs     

DS Martins  CE Ambrósio  NZ Saraiva  CV Wenceslau  AC Morini  I Kerkis  JM Garcia  MA Miglino 《Reproduction in domestic animals》2011,46(1):e62-e66

Previously, three distinct populations of putative primordial germ cells (PGCs), namely gonocytes, intermediate cells and pre‐spermatogonia, have been described in the human foetal testis. According to our knowledge, these PGCs have not been studied in any other species. The aim of our study was to identify similar PGC populations in canine embryos. First, we develop a protocol for canine embryo isolation. Following our protocol, 15 canine embryos at 21–25 days of pregnancy were isolated by ovaryhysterectomy surgery. Our data indicate that dramatic changes occur in canine embryo development and PGCs specification between 21 to 25 days of gestation. At that moment, only two PGC populations with distinct morphology can be identified by histological analyses. Cell population 1 presented round nuclei with prominent nucleolus and a high nuclear to cytoplasm ratio, showing gonocyte morphology. Cell population 2 was often localized at the periphery of the testicular cords and presented typical features of PGC. Both germ cell populations were positively immunostained with anti‐human OCT‐4 antibody. However, at day 25, all cells of population 1 reacted positively with OCT‐4, whereas in population 2, fewer cells were positive for this marker. These two PGCs populations present morphological features similar to gonocytes and intermediate cells from human foetal testis. It is expected that a population of pre‐spermatogonia would be observed at later stages of canine foetus development. We also showed that anti‐human OCT‐4 antibody can be useful to identify canine PGC in vivo.  相似文献   

Aboveground growth interactions of paired conifer seedlings in close proximity     

Warren D. Devine  Timothy B. Harrington 《New Forests》2011,41(2):163-178

Where belowground resources are relatively abundant, naturally established trees sometimes occur in very close proximity to one another. We conducted a two-year study to assess the aboveground interactions between Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis) and noble fir (Abies procera) seedlings planted in closely spaced (stems 10 cm apart) conspecific and heterospecific pairs. Paired seedling growth also was compared to seedlings planted with no neighbor. Stem height growth was not affected by the presence of a neighbor seedling, although diameter growth was slightly reduced. Branch diameter growth and weight were reduced where seedling crowns overlapped; branch morphological data suggested that this was caused by shading rather than mechanical interactions. Light measurements showed the potential for significant shading, particularly by the relatively large, dense crowns of Douglas-fir. Heterospecific pairs including Douglas-fir demonstrated the competitive production principle in that their mean growth was greater than the average of conspecific pairs of both species. Neighbor seedling height significantly affected subject seedling growth; neighbor effects were similar whether the neighbor seedling was growing on the north or south side of the subject seedling. Light reflected from Douglas-fir crowns had a lower red: far-red ratio than that of noble fir, although there was no evidence of a phytochrome-mediated growth response to the neighbor seedling. While heterospecific seedling pairs showed reduced competition, we found no evidence of facilitation for seedlings growing in very close proximity.  相似文献   

关于内蒙古大兴安岭林区实施森林抚育补贴项目的探讨   总被引：2，自引：0，他引：2  

策日格 《内蒙古林业调查设计》2011,(4):9-11,15

文章通过对内蒙古大兴安岭林区实施森林抚育补贴项目的背景、必要性的分析,论述了森林抚育是促进林区生态、经济和社会协调发展的有力措施。  相似文献   

Insecticide use: Contexts and ecological consequences   总被引：2，自引：0，他引：2  

Gregor J. Devine  Michael J. Furlong 《Agriculture and Human Values》2007,24(3):281-306

Constraints to the sustainability of insecticide use include effects on human health, agroecosystems (e.g., beneficial insects), the wider environment (e.g., non-target species, landscapes and communities) and the selection of insecticide-resistant traits. It is possible to find examples where insecticides have impacted disastrously on all these variables and others where the hazards posed have been (through accident or design) ameliorated. In this review, we examine what can currently be surmised about the direct and indirect long-term, field impacts of insecticides upon the environment. We detail specific examples, describe current insecticide use patterns, consider the contexts within which insecticide use occurs and discuss the role of regulation and legislation in reducing risk. We consider how insecticide use is changing in response to increasing environmental awareness and inevitably, as we discuss the main constraints to insecticide use, we suggest why they cannot easily be discarded. Gregor Devine has an MSc in pest management and a PhD in applied entomology from Imperial College, London. He is a Senior Research Scientist employed by Rothamsted Research, UK. He is currently investigating novel disease vector control methods in Peru in association with the US Naval Medical Research Center Detachment, the Peruvian Ministry of Health, the University of California-Davis, and the US Centers for Disease Control. Michael Furlong has an MSc in pest management and a PhD in applied entomology from Imperial College, London. He is a Lecturer and Researcher in the School of Integrative Biology at the University of Queensland, Australia. His research interests include biological control, and the design and implementation of sustainable Integrated Pest Management strategies for international development. He works in Australia, China, North Korea and the Pacific Islands.  相似文献   

Insecticide resistance in Egyptian populations of the cotton whitefly,Bemisia tabaci (Hemiptera: Aleyrodidae)     

El Kady H  Devine GJ 《Pest management science》2003,59(8):865-871

Three collections of Bemisia tabaci were taken from cotton and vegetable crops at the beginning of the growing season in Egypt. These displayed marked resistance to the carbamates carbosulfan (ca 20- to 50-fold) and aldicarb (ca 40- to 80-fold) and moderate resistance to the pyrethroids cypermethrin (ca 10- to 30-fold) and lambda-cyhalothrin (ca 10- to 25-fold). They displayed no resistance to the organophosphates profenofos and pirimiphos-methyl, or to imidacloprid. Another population, collected at the end of the growing season, differed markedly in its response. In this population, resistance to carbosulfan remained high (ca 40-fold), resistance to profenofos and cypermethrin was increased (ca 20- and 50-fold respectively) and a slight resistance to imidacloprid was detected (ca 6-fold). Resistance to cypermethrin and profenofos was shown to be similar among adults and nymphs. Irrespective of collection date, none of the populations showed resistance to pyriproxyfen. These Egyptian populations were compared with two representative Israeli populations. The differences between their resistance profiles is discussed in terms of their collection date, their geographical proximity and the patterns of insecticide use at their sites of collection.  相似文献   

Gravitational inconsistency in the lunar theory: numerical determination     

Mulholland JD  Devine CJ 《Science (New York, N.Y.)》1968,160(3830):874-875

Preliminary numerical integrations of the lunar motion indicate that defects in the lunar ephemeris, due to omissions in the revised Brown lunar theory, produce errors of the order of several hundred meters in the coordinates at certain times. Such errors are large enough to affect adversely analyses of data from spacecraft, as well as determination of ephemeris time. Distinct planetary periodicities seem to appear in the residuals.  相似文献   

Determination of trichlorfon (0,O-dimethyl (2,2,2-trichloro-1-hydroxyethyl)phosphonate) in forest environmental samples     

J M Devine 《Journal of agricultural and food chemistry》1973,21(6):1095-1098

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L7-S1 fixation-fusion for treatment of cauda equina compression in the dog     

B Slocum  T Devine 《Journal of the American Veterinary Medical Association》1986,188(1):31-35

The L7-S1 fixation-fusion technique for treatment of cauda equina compression was performed on 14 dogs, 13 of which were 6 years old or older, were severely lame, and had ventral bridging spondylitis at the L7-S1 vertebrae. One dog, 3 months old, had a congenital malformation of the L7 vertebra. The principles of the L7-S1 fusion technique were to expand the L7-S1 intervertebral foramina and spinal canal, remove pressure on the nerve roots, and provide stability to the L7-S1 vertebrae. This technique appeared to be applicable clinically for restoring normal function and activity to dogs with cauda equina compression.  相似文献   

Identification of surface morphologic changes in the mitral valve leaflets and chordae tendineae of dogs with myxomatous degeneration     

Corcoran BM  Black A  Anderson H  McEwan JD  French A  Smith P  Devine C 《American journal of veterinary research》2004,65(2):198-206

OBJECTIVE: To describe structural changes in the left atrioventricular (mitral) valve complex of dogs with endocardiosis by use of scanning electron microscopy. ANIMALS: 5 clinically normal dogs and 4 dogs with mitral valve endocardiosis. PROCEDURE: The mitral valve complex from each dog was fixed and prepared for examination via scanning electron microscopy. Findings in valves from clinically normal and affected dogs were compared to identify surface changes associated with endocardiosis. RESULTS: Compared with findings in valves from clinically normal dogs, endocardiosis-affected mitral valve complexes had several morphologic abnormalities. Tissue swelling on the edge of valve leaflets, chordae tendineae, and the chordal-papillary muscle junction was evident. Damage to the valve complex endothelium was unevenly distributed; in some areas, denudation of endothelial cells had exposed the basement membrane or subendothelial valve collagen matrix. This damage was most noticeable on the leaflet edges and extended more to the ventricular aspect of the valve than the atrial side. Cell loss also extended to the chordae tendineae but was less apparent at the chordal-papillary muscle junction. The remaining endothelial cells on affected valves were arranged in less-ordered rows and had more plasmalemmal microappendages, compared with cells on unaffected valves. CONCLUSIONS AND CLINICAL RELEVANCE: Morphologic changes associated with mitral valve endocardiosis in dogs were similar to those observed in humans with mitral valve prolapse. In dogs with mitral valve endocardiosis, gross changes in the valve complex may affect hemodynamics in the heart; alterations in the leaflet and chordal endothelium may contribute to pathogenesis of this disease.  相似文献   

Electroencephalograms and electrocardiograms in young bulls following upper cervical vertebrae-to-brisket stunning     

Cook CJ  Devine CE  Gilbert KV  Tavener A  Day AM 《New Zealand veterinary journal》1991,39(4):121-125

Passing an electric current (50 Hz, 400 V open circuit, current limited to 1.5 A) from two electrodes acting as a common single electrode set applied on each side of the dorsal surface of the neck (cervical vertebrae C2 to C5 region) to another placed on the brisket of young bulls causes fibrillation of the cardiac muscle, does not induce epileptiform changes in the electroencephalogram, and produces a state of body rigidity. Passing the same electric current through the same neck electrodes, now acting as two separate electrodes, without the brisket electrode, does induce epileptiform activity similar to that seen with head-only stunning, does not fibrillate the heart, and produces a state of limb rigidity lasting for some time after the stun. Given that the presence of epileptiform activity is a criterion for effective electrical stunning and is indicative of insensibility, neck-to-brisket stunning as described here does not appear to be humane.  相似文献